1. Technical Field
The present invention relates to a method of manufacturing a loudspeaker for an in-car application or used in various audio equipment and the like.
2. Background Art
In recent years, in the automobile industry and the audiovisual industry, downsizing of automobiles, electronic devices such as audiovisual equipment, and loudspeakers used for such applications has been demanded in order to promote energy savings and to improve environmental responsiveness and a space factor. At the same time, high maximum input power, high quality, and high reliability are also demanded in order to improve performance of loudspeakers.
In the following, a conventional method of manufacturing a loudspeaker is described with reference to the drawings. FIG. 8 is a chart showing steps of the conventional method of manufacturing a loudspeaker. FIG. 9 is a cross-sectional view illustrating a loudspeaker manufactured through the conventional method of manufacturing a loudspeaker.
As illustrated in FIG. 8 and FIG. 9, first, magnetic circuit 104 is assembled by attaching magnet 101 and plate 102 to yoke 103. At this time, plate 102 and yoke 103 are attached without decentering by guiding an outer circumference of plate 102 and an inner circumference of yoke 103 by a gap gauge (not depicted) such that a size of magnetic gap 105 of magnetic circuit 104 is accurately ensured.
Next, yoke 103 of magnetic circuit 104 is inserted into a central portion of an inner bottom surface of frame 106 along a side of a yoke insertion portion of frame 106, and coupled by an adhesive agent.
Then, an assembly of voice coil 108 and damper 109 that have been assembled through another step is attached to a damper attachment portion of frame 106. At this time, by guiding an inner circumference of voice coil 108 and the outer circumference of plate 102 by a spacer (not depicted), voice coil 108 is inserted into magnetic gap 105 so as not to be decentered.
Next, diaphragm 107 is coupled to a peripheral portion of frame 106 via an edge, and diaphragm 107 is coupled to voice coil 108 for driving diaphragm 107.
Finally, dust cap 110 is coupled to a front surface of diaphragm 107, and thus a loudspeaker is completed.
Here, known information of prior art documents relating to the present invention includes PTL 1, for example.
However, according to the conventional method of manufacturing a loudspeaker, if yoke 103 of magnetic circuit 104 is obliquely coupled to the central portion of the inner bottom surface of frame 106 when assembling magnetic circuit 104 and frame 106, a gap defect occurs due to the obliquity.
Conceivable factors of such obliquity include dimensional tolerance of component parts such as frame 106, yoke 103, magnet 101, and plate 102, and accumulation of obliquity and displacement occurring when these component parts are coupled.
Additionally, the factors can include an uneven condition of the attachment between the central portion of the inner bottom surface of frame 106 and yoke 103 of magnetic circuit 104 due to uneven thickness of an adhesive agent applied to the central portion of the inner bottom surface of frame 106. Specifically, even if the size of magnetic gap 105 of magnetic circuit 104 is accurately ensured, magnetic circuit 104 and frame 106 are often assembled obliquely in this manner. In such a case, when voice coil 108 vibrates up and down, voice coil 108 is brought into contact with magnetic gap 105 to generate a gap defect. Here, the generation of the gap defect tends to be more noticeable as amplitude of a voice coil in a magnetic gap becomes larger due to downsizing and increased maximum input power of a loudspeaker.